Microbicidal compositions

ABSTRACT

The combination of the plant microbicide 3-cyano-4-(2,3-dichlorophenyl)-pyrrole (&#34;fenpiclonil&#34;) with the plant microbicide 1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-1,3-dioxolan-2-ylmethyl}-1H-1,2,4-triazole results in a synergistrically enhanced activity in the control of plant diseases. Plant microbicidal compositions based on such combinations are especially suitable for treating seed.

The present invention relates to microbicidal mixtures havingsynergistically enhanced activity against plant diseases and to methodsof using such mixtures, especially for dressing seed.

The invention relates especially to the control or prevention ofdiseases in cereal cultivation.

It has been found that a combination of the active ingredient componentI), 3-cyano-4-(2,3-dichlorophenyl)-pyrrole ("fenpiclonil") of formula I##STR1## with the active ingredient component II),1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-1,3-dioxolan-2-ylmethyl}-1H-1,2,4-triazoleof formula II ##STR2## or with a salt thereof results in asynergistically enhanced activity in the control and prevention of plantdiseases.

The compound of formula I is mentioned in DE-OS No. 2,927,480 (or in GBPatent Application No. 2,024,824) among other intermediates. Its use asa fungicidal active ingredient is described in EP-A No. 236272. It isdistinguished especially as a contact fungicide.

The compound of formula II is described as a fungicidal activeingredient in GB Patent Application No. 2,098,607. The action of thattriazole derivative is based on the inhibition of ergosterolbiosynthesis.

The mentioned salts of the compound of formula II can be prepared byreacting the base with acids.

Of the acids that may be used for the preparation of salts of formula IIthere may be mentioned: hydrohalic acid, such as hydrofluoric acid,hydrochloric acid, hydrobromic acid or hydriodic acid and sulfuric acid,phosphoric acid, nitric acid and organic acids, such as acetic acid,trifluoroacetic acid, trichloroacetic acid, propionic acid, glycolicacid, thiocyanic acid, lactic acid, succinic acid, citric acid, benzoicacid, cinnamic acid, oxalic acid, formic acid, benzenesulfonic acid,p-toluenesulfonic acid, methanesulfonic acid, salicylic acid,p-aminosalicylic acid, 2-phenoxybenzoic acid, 2-acetoxybenzoic acid or1,2-naphthalenedisulfonic acid.

The term "salts" also includes metal complexes of the basic componentII. Those complexes consist of the fundamental organic molecule and aninorganic or organic metal salt, for example the halides, nitrates,sulfates, phosphates, acetates, trifluoroacetates, trichloroacetates,propionates, tartrates, sulfonates, salicylates, benzoates, etc. ofelements of the second main group, such as calcium and magnesium, and ofthe third and fourth main groups, such as aluminium, tin or lead, and ofthe first to eighth sub-groups, such as chromium, manganese, iron,cobalt, nickel, copper, zinc, etc. The sub-group elements of the 4thperiod are preferred. The metals may be present in any of the variousvalencies attributed to them. The metal complexes may be mono- orpoly-nuclear, that is to say they may contain one or more organicmolecular components as ligands.

It is known to the person skilled in the art that the activity of afungicidal active ingredient can be greatly enhanced or broadened by theaddition of another fungicide having a different spectrum of activity.

It has surprisingly been found, however, that the combination of theactive ingredients I and II results in a quite unexpectedly substantialenhancement of activity against seed-borne and soil-borne fungi. Theenhabncement of activity achieved by the combination according to theinvention is distinctly greater than the activity that would be expectedfrom the addition of the activities of the two individual components,that is to say, the combination has synergistic activity.

Apart from synergistic fungicidal activity, the mixtures according tothe invention exhibit a pronounced plant growth promoting activity whichdepends on the composition of the mixture according to the invention toapproximately the same extent as does the fungicidal activity.Accordingly, the plant growth promoting activity of the mixturesaccording to the invention can also be regarded as synergistic.

The present invention therefore permits the dressing of seeds with loweramounts of biocides than known hitherto and therefore constitutes a verysubstantial enrichment of the state of the art.

The present invention reltates not only to the application of mixturesof components I and II to seed but also to the application of theindividual pure components in immediate succession.

Favourable ratios of the two active ingredients are I:II=20:1 to 1:20,especially I:II=10:1 to 1:10 and very especially I:II=5:1 to 1:5. Otheradvantageous ratios are I:II=5:2 to 2:5 or 3:2 to 2:3 or 1:1.

An enhanced activity is also observed when the compound of formula I iscombined with other active ingredients, provided the latter areinhibitors of demethylation by the ergosterol synthesis route of fungi.Such demethylation inhibitors are bitertanol, diniconazole,ethyltrianol, flutriafol, flusilazole, furconazole, imazalil,myclobutanil, cyproconazole, triadimefon, triadimenol and others, whosestructure and fungicidal activity are know to the person skilled in theart.

The combinations of active components I and II according to the presentinvention have useful contact action and systemic and long-lastingaction in the control of seed-borne and soil-borne plant diseases.Microorganisms in the seed are destroyed and plants in the process ofdeveloping are protected from attack by soil-borne microorganisms by thecombinations according to the invention.

The mixtures according to the invention are effective againstphytopathogenic fungi belonging to the following classes: Ascomycetes(e.g. the genera Mycosphaerella, Pyrenophora); Basidiomycetes (e.g. thegenera Tilletia, Rhizoctonia); Fungi imperfecti (e.g. the generaFusarium, Septoria, Phoma, Alternaria). The combinations according tothe invention are especially effective in seed treatment (fruit, tubers,grains), activity against Fusarium nivale on wheat being especiallypronounced. They are, however, also suitable for direct treatment of thesoil or other plant parts. They are well tolerated by plants and areecologically non-harmful.

In practice, the mixture according to the invention is normally usedtogether with the adjuvants customarily employed in the art offormulation. The active components of formulae I and II are formulatedin known manner, e.g. to emulsifiable concentrates, coatable pastes,directly sprayable or dilutable solutions, dilute emulsions, wettablepowders, soluble powders, dusts, granulates, and also encapsulations in,e.g., polymer substances. The methods of application, such as spraying,atomising, dusting, scattering, coating or pouring, and the form of thecomposition are in accordance with the intended objectives and theprevailing circumstances. Advantageous rates of application aregenerally from 0.0005 to a maximum of 0.5 kg, especially from 0.001 to0.01 kg of each of active ingredients I and II per 100 kg of material tobe protected. The application conditions depend to a very considerableextent, however, on the nature (size of the surface, consistency,moisture content) of the material and on environmental factors.

Within the scope of the present invention, stored and stock materialsand especially seed are to be understood as being natural plant and/oranimal substances and products of their further processing, for examplethe following plants and their parts, (stems, leaves, tubers, seed,fruit, grains) which have been taken from the natural life cycle andwhich are present in the freshly harvested state or in further processedform (pre-dried, moistened, pulverised, ground, roasted, etc.).

Target crops to be protected within the scope of this invention comprisee.g. the following species of plants: cereals: (wheat, barley, rye,oats, rice, sorghum, maize and related crops); beet: (sugar beet andfodder beet); leguminous plants: (beans, lentils, soybeans, peas); oilplants: (rape, mustard, poppy, sunflowers); cucumber plants: (marrows,cucumbers, melons); fibre plants: (cotton, flax); vegetables: (lettuce,cabbages, spinach, carrots, onions, tomatoes, potatoes, paprika);ornamentals: (tulips, daffodils, dahlias, chrysanthemums and otherflowers) and spice plants and their seeds.

A preferred method of applying the mixture according to the inventionconsists in spraying or wetting the plant material with a liquidformulation or in mixing the plant material with a solid formulation ofthe active ingredient. The described method of preservation forms partof the present invention.

The compounds of formulae I and II are used according to the inventionin the form of compositions and may be employed optionally together withfurther carriers, surfactants or other application-promoting adjuvantscustomarily used in the art of formulation.

Suitable carriers and adjavants can be solid or liquid and correspond tothe substances expediently employed in formulation technology, e.g.natural or regenerated mineral substances, solvents, dispersants,wetting agents, tackifiers, thickeners, binders or fertilisers.Phospholipids are especially advantageous adjuvants.

A preferred method of applying a mixture of compounds of formulae I andII, or an (agro)chemical composition which contains these compounds, isfoliar application. The number of applications and the rate ofapplication depend on the risk of infestation by the correspondingpathogen (species of fungus). However, the active ingredient mixture canalso penetrate the plant through the roots via the soil (systemicaction) by impregnating the locus of the plant with a liquidformulation, or by applying the compounds in solid form to the soid,e.g. in granular form (soil application). The mixture of the compoundsof formulae I and II can, according to an especially preferred method,be applied to seed grains, tubers, fruit or other plant material to beprotected (coating) either by impregnating the material with a liquidformulation of the active ingredients or by coating it with a solidformulation. In special cases, further types of application are alsopossible, for example selective treatment of the plant stems or buds.

The compounds of formulae I and II are used in unmodified form or,preferably, together with the adjuvants conventionally employed in theart of formulation, and are therefore formulated in known manner e.g.into emulsifiable concentrates, coatable pastes, directly sprayable ordilutable solutions, dilute emulsions, wettable powders, solublepowders, dusts, granulates, and also encapsulations in e.g. polymersubstances. As with the nature of the compositions, the methods ofapplication, such as spraying, atomising, dusting, scattering, coatingor pouring, are chosen in accordance with the intended objectives andthe prevailing circumstances. Advantageous rates of application in thecase of field treatment are normally from 5 g to 5 kg of activeingredient (a.i.) of formulae I and II per hectare, preferably from 10 gto 2 kg a.i./ha, most preferably from 20 g to 600 g a.i./ha.

The formulations, i.e. the compositions, preparations or mixturescontaining the compound (active ingredient) of formulae I and II and,where appropriate, a solid or liquid adjuvant, are prepared in knownmanner, e.g. by homogeneously mixing and/or grinding the activeingredients with extenders, e.g. solvents, solid carriers and, whereappropriate, surface-active compounds (surfactants).

Suitable solvents are: aromatic hydrocarbons, preferably the fractionscontaining 8 to 12 carbon atoms, e.g. xylene mixtures or substitutednaphthalenes, phthalates such as dibutyl phthalate or dioctyl phthalate,aliphatic hydrocarbons such as cyclohexane or paraffins, alcohols andglycols and their ethers and esters, such as ethylene glycol monomethylether, ketones such as cyclohexanone, strongly polar solvents such asN-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethylformamide, as wellas vegetable oils or epoxidised vegetable oils, or soybean oil; orwater.

The solid carriers used e.g. for dusts and dispersible powders, arecalcite, talcum, kaolin, montmorillonite or attapulgite, highlydispersed silicic acid or absorbent polymers. Suitable granulatedadsorptive carriers are pumice, broken brick, sepiolite or bentonite;and suitable nonsorbent carriers are, for example, calcite or dolomite.

Depending on the nature of the compounds of formulae I and II to beformulated, suitable surface-active compounds are non-ionic, cationicand/or anionic surfactants having good emulsifying, dispersing andwetting properties. The term "surfactants" will also be understood ascomprising mixtures of surfactants.

The surfacetants customarily employed in the art of formulation haveappeared, inter alia, in the following publications:

"Mc Cutcheon's Detergents and Emulsifiers Annual" MC Publishing Corp.,Ridgewood New Jersey, 1980.

Sisley and Wood, "Encyclopedia of Surface Active Agents", ChemicalPublishing Co. Inc., New York, 1980.

Especially advantageous application-promoting adjuvants are also naturalor synthetic phospholipids from the series of the cephalins andlecithins, e.g. phosphatidylethanolamine, phosphatidylserine,phosphatidylglycerol and lysolecithin.

The agrochemical compositions usually contain 0.1 to 99%, preferably 0.1to 95%, of a compound of formula I, 99.9 to 1%, preferably 99.9 to 5%,of a solid or liquid adjuvant, and 0 to 25%, preferably 0.1 to 25%, of asurfactant.

Whereas commercial products will preferably be formulated asconcentrates, the end user will normally employ dilute formulations.

Such (agro)chemical compositions form part of the present invention.

The following Examples serve to illustrate the invention, "activeingredient" denoting a mixture of "fenpiclonil" I and compound II in aspecific ratio of 10:1 to 1:10.

    ______________________________________                                        Wettable powders   (a)      (b)    (c)                                        ______________________________________                                        active ingredient (I:II =                                                                        25%      50%    75%                                        10:1, 5:2, 1:3)                                                               sodium lignosulfonate                                                                             5%       5%    --                                         sodium laurylsulfate                                                                              3%      --      5%                                        sodium diisobutylnaphthalene-                                                                    --        6%    10%                                        sulfonate                                                                     octylphenol polyethylene glycol                                                                  --        2%    --                                         ether (7-8 moles of ethylene oxide)                                           highly dispersed silicic acid                                                                     5%      10%    10%                                        kaolin             62%      27%    --                                         ______________________________________                                    

The active ingredient is thoroughly mixed with the adjuvants and themixture is thoroughly ground in a suitable mill, affording wettablepowders which can be diluted with water to give suspensions of thedesired concentration.

    ______________________________________                                        Emulsifiable concentrate                                                      ______________________________________                                        active ingredient (I:II = 1:20)                                                                         10%                                                 octylphenol polyethylene glycol                                                                          3%                                                 ether (4-5 moles of ethylene oxide)                                           calcium dodecylbenzenesulfonate                                                                          3%                                                 castor oil polyglycol ether                                                                              4%                                                 (35 moles of ethylene oxide)                                                  cyclohexanone             30%                                                 xylene mixture            50%                                                 ______________________________________                                    

Emulsions of any required concentration can be obtained from thisconcentrate by dilution with water.

    ______________________________________                                        Dusts                   (a)    (b)                                            ______________________________________                                        active ingredient (I:II = 2:3 and 1:1)                                                                 5%     8%                                            talcum                  95%    --                                             kaolin                  --     92%                                            ______________________________________                                    

Ready-for-use dusts are obtained by mixing the active ingredient withthe carrier and grinding the mixture in a suitable mill.

    ______________________________________                                        Extruder granulate                                                            ______________________________________                                        active ingredient (I:II = 20:1)                                                                         10%                                                 sodium lignosulfonate      2%                                                 carboxymethylcellulose     1%                                                 kaolin                    87%                                                 ______________________________________                                    

The active ingredient is mixed and ground with the adjuvants, and themixture is subsequently moistened with water. The mixture is extrudedand then dried in a stream of air.

    ______________________________________                                        Coated granulate                                                              ______________________________________                                        active ingredient (I:II = 3:2)                                                                           3%                                                 polyethylene glycol (mol. wt. 200)                                                                       3%                                                 kaolin                    94%                                                 ______________________________________                                    

The finely ground active ingredient is uniformly applied, in a mixer, tothe kaolin moistened with polyethylene glycol. Non-dusty coatedgranulates are obtained in this manner.

BIOLOGICAL EXAMPLES

A synergistic effect has been achieved with fungicides whenever thefungicidal action of the combination of active ingredients is greaterthan the sum of the action of the active ingredients appliedindividually.

The expected action E for a given combination of active ingredients, forexample of two fungicides, obeys the so-called COLBY formula and can becalculated as follows (COLBY, L. R., "Calculating synergistic andantagonistic responses of herbicide combination". Weeds 15, pages20-22.2) (LIMPEL et al., 1062 "Weeds control by . . . certaincombinations". Proc. NEWCL, Vol 16, pp. 48-53):

(g a.i./hl=gram of active ingredient per hectoliter of spray mixture)

X=% action of fungicide I at p g a.i./ha

Y=% action of fungicide II at q g a.i./ha

E=expected action of fungicides I+II at a rate of application of p=q ga.i./ha (additive action)

then according to Colby: ##EQU1##

If the action actually observed (O) is greater than the expected action,then the action of the combination is greater than additive, e.g. thereis a synergistic effect.

Fungicidal activity against seed-borne Septoria nodorum on winter wheat

The wheat seed ("Moleson" variety) infected with Septoria nodorum isharvested from the field. The malt-agar test shows that the seed is 53%infected. The seed is treated with mixtures of the active ingredients asshown in the following Table. To ensure uniform treatment, the activecomponents are first dispersed in water and then sprayed onto the seedwhich is on a rotating bed. This procedure corresponds to standardconventional practice.

The treated seed is sown in arable soil. The arable soil is placed indishes of the following size: depth 11 cm, length 40 cm, width 30 cm.100 grains are used in each dish and three parallel tests are carriedout for each combination.

The efficacy of the individual products is assessed using the methoddisclosed by Holmes and Coloun (S. J. I. Holmes and J. Colhoun: "Amethod for assessing the efficacy of seed infectants for the control ofseed-borne Septoria nodorum on wheat". Annals of Applied Biology 75 pp.225-232, 1973).

After sowing, the dishes are kept for two weeks at from 8 ° to 10° C.with the exclusion of light and are then placed in a greenhouse and keptthere at 20° C. for a further two weeks. The seedlings are then takenfrom the soil and washed. The degree of damage to these plants iscompared with the degree of fungus attack in the untreated controlplants.

                                      TABLE                                       __________________________________________________________________________           g active ingredient                                                                             action E                                                    100 kg seed  fungus                                                                             (calculated)                                                                        action O                                       treatment                                                                            component                                                                            component                                                                           attack                                                                             (%)   (found)                                        no.    I      II    (%)  (COLBY)                                                                             (%)                                            __________________________________________________________________________    1. comparison                                                                        --     --    100  --    --                                             2.     1      --    88   --    12                                             3.     2      --    87   --    13                                             4.     5      --    65   --    35                                             5.     10     --    54   --    46                                             6.     --     1     37   --    63                                             7.     --     2     27   --    73                                             8.     --     5     17   --    83                                             9.            10     7   --    93                                             10.    1      1     29   67    71                                             11.    1      2     18   77    82                                             12.    1      5     10   85    90                                             13.    2      2     14   77    86                                             14.    5      1     19   75    81                                             15.    5      2     12   82    88                                             16.    5      5      7   89    93                                             17.    10     1     17   80    83                                             18.    10     2     10   86    90                                             __________________________________________________________________________

As can be seen from the Table, treatments nos. 10-18, in whichcomponents I and II were used in a wide variety of ratios, exhibit anenhanced, i.e. synergistic, activity.

Similarly enhanced, i.e. synergistic, activity is exhibited against snowmould (Gerlachia nivalis) on wheat, barley and rye, against Pyrenophoragraminea and P. teres on barley, against Tilletia caries on wheat andagainst other seed-borne and soil-borne pathogens.

What is claimed is:
 1. A fungicidal composition for plants containing asynergistic fungicidally effective amount of the mixture of at least twoactive ingredient components, wherein one component (I) is3-cyano-4-(2,3-dichlorophenyl)-pyrrole of formula I ##STR3## and theother component (II) is1-{2-[2-chloro-4-(4-chlorophenoxy)-phenyl]-4-methyl-1,3-dioxolan-2-ylmethyl}-1H-1,2,4-triazoleof formula II ##STR4## or a salt thereof, together with carrier, whereinthe weight ratio of I:II is 20:1 to 1:20.
 2. The composition accordingto claim 1, wherein the weight ratio of I:II is 5:1 to 1:5.
 3. A methodof controlling or preventing plant fungal diseases, which comprisestreating the plant locus which is already infected, or is liable to beinfected, in any order or simultaneously with a synergistic fungicidallyeffective amount of the composition of claim
 1. 4. The method accordingto claim 3, which comprises treating the seed.